There is one big difference between Republican John McCain and the Democratic yet to be named candidate. The Democrats promise to recall our troops from Iraq as soon as possible (ASAP) where as McCain promises to prosecute the war until victory is achieved. Election day promises don't come much clearer than that.
Elect a Democrat and the troops pull out. Then Al Quada or Iran takes over Iraq, all the Iraqis who have worked with the Americans are murdered, the country dissolves into a Sunni Shia civil war. The entire Arab world gets an object lesson in what happens to anyone who co operates with the Americans, namely the Americans will go home and leave you twisting in the breeze. This will demoralize even the Israelis, let alone any Sunni Arab government. Iran brings their nuclear weapons program to fruition, and pressures all the middle east countries to knuckle under to them. Think oil is expensive today? Wait til Iran shows up at the next OPEC meeting, armed with nuclear weapons, the Americans totally discredited, and demands cutting production and hiking the price. The Saudi's wouldn't dare oppose Iran in those circumstances. If that isn't bad enough, think about where we go if the Iranians carry thru on their pledge to nuke Israel out of existence.
On the other hand, sticking it out in Iraq will deal Bin Ladin's Islamo Fascist movement a mortal blow. Just this last month the Iraqi government finally gained the strength to confront its enemies, the militias and gangsters still holding out. The Iraqi government is the first real democracy in the Arab world. If it survives, Iraq will become the most desirable place to live in all the Middle East. A peaceful and prosperous democratic Iraq would set a powerful example to the entire Arab world. So powerful that the Arab dictatorships (every other Arab country is a dictatorship) would be under enormous pressure to emulate Iraq's democracy.